Why does the red rear light of a F1 car blink/flash in dry conditions?

The red back light seems to blink randomly in dry conditions. Why is this?

It is a safety feature. The regulations state that when the driver is conserving fuel, the light at the rear of the car must blink. It is kind of a warning for the other drivers, if the driver is slowing down at the end of the straight. The driver is slowing down, but not really braking down.